The present invention generally relates to numbering machines, and more particularly the invention relates to a numbering machine including a check digit printing mechanism whereby when a code number is printed, an associated check digit is printed simultaneously.
Generally, the check digits used for coding error detecting purposes each consists of a single-place digit calculated from the figure of the corresponding code number and it is for example appended to the right of the least significant digit of the code number. In other words, a check digit is appended to an important key number such as an account number or customer code number and the check digits are used for the purpose of detecting coding errors caused during the computer processing. Included among the known methods of forming check digits are modulus 10 checks typical of which is the Luhn's check as well as modulus 11 checks. With a 9's check or a 7's check, a particular sequence of digits is simply circulated in response to changes of code numbers, and since it is only necessary to arrange so that a check digit type wheel for printing check digits is intermittently rotated in the same manner as the least significant digit numbering type wheel of a print unit, the mechanism of a numbering machine is simple and this type of machine has already been put in practical use.
On the other hand, with each of the modulus 10 check and the modulus 11 check, while the check digits are calculated in correspondence with the code numbers by using a predetermined weighting method and consequently a predetermined sequence of digits is circulated to print the check digits, there occur singular points at which a discontinuous change is caused in the circulating sequence of digits when going from one code number to the next code number, thus making it difficult to realize a numbering machine as compared with that according to the 9's check. As a result, no practical numbering machine has been put in use which is capable of continuously printing the desired check digits according to the modulus 10 check or the modulus 11 check, and in the actual business data processing a technique has been used in which each code number to be printed is appended with a check digit calculated by a calculation method based on a predetermined modulus and weights. As a result, much time and labor have been required for the calculation and printing of check digits, and particularly in the case of a rotary press or the like it has been nearly impossible to print each code number and its associated check digit simultaneously.